What should you do when you see a sign marked 'W'?

When encountering a sign marked 'W', the appropriate action is to sound the horn in accordance with Rule 156G. This rule is typically related to audibly alerting other personnel or passing trains in situations where visibility or awareness may be compromised. The horn serves as an essential safety signal, ensuring that all individuals in proximity to the train are alerted and can react appropriately, particularly in areas where the sign 'W' indicates a relevant warning or necessary precaution.

The focus on sounding the horn rather than immediately reducing speed or taking other actions emphasizes the importance of communication in ensuring the safety of both the train crew and passengers. Sensory awareness, through auditory signals, plays a crucial role in rail operations, where train movements can have rapid and direct implications for safety.

While other options may appear relevant in different contexts, the specific action associated with the 'W' sign is firmly established by protocol, highlighting the universal importance of operational signaling in railway practices.